Step 1
Prepare the grill for indirect grilling at 350°F air temperature with wood smoke. Pecan wood is a good choice.
Step 2
To make the topping, combine the dry ingredients in a mixing bowl. Cut the butter into 12 to 16 pieces and cut into the mixture with a pastry cutter. Cut until the texture is relatively fine but don’t completely break down the butter. Stir in the buttermilk with a spoon to finish the dough. Set off to the side.
Step 3
To make the filling, whisk together all of the ingredients except the peaches. Gently fold in the peaches last.
Step 4
Pour the peach filling into a greased 12-inch cast-iron skillet. Drop spoonfuls of the topping over the top. Transfer to the indirect zone of the grill with the smoke going and close the lid. Bake, rotating occasionally, until bubbly and golden brown, about 40 minutes.
Step 5
Serve warm with ice cream.